Identification of a proton sensor that regulates conductance and open time of single hERG channels.

The hERG potassium channel influences ventricular action potential duration. Extracellular acidosis occurs in pathological states including cardiac ischaemia. It reduces the amplitude of hERG current and speeds up deactivation, which can alter cardiac excitability. This study aimed to identify the site of action by which extracellular protons regulate the amplitude of macroscopic hERG current. Recordings of macroscopic and single hERG1a and 1b channel activity, mutagenesis, and the recent cryoEM structure for hERG were employed. Single hERG1a and 1b channels displayed open times that decreased with membrane depolarization, suggestive of a blocking mechanism that senses approximately 20% of the membrane electric field. This mechanism was sensitive to pH; extracellular acidosis reduced both hERG1a and1b channel open time and conductance. The effects of acidosis on macroscopic current amplitude and deactivation displayed different sensitivities to protons. Point mutation of a pair of residues (E575/H578) in the pore turret abolished the acidosis-induced decrease of current amplitude, without affecting the change in current deactivation. In single hERG1a channel recordings, the conductance of the double-mutant channel was unaffected by extracellular acidosis. These findings identify residues in the outer turret of the hERG channel that act as a proton sensor to regulate open time and channel conductance.

Effects of Vaginal Lubricants on In-Vitro Progressive Spermatozoa Motility.

Vaginal lubricants are used to solve intercourse difficulties or as sexual enhancers, but recent reports raise questions about their safety in terms of fertility. In this study, twenty semen samples were tested against commercially available vaginal lubricants for progressive spermatozoa motility and vitality with varying exposure time intervals. Results showed that the vaginal lubricant which least affected progressive spermatozoa motility was the oil-based vaginal lubricant, which kept the mean percentage of progressive spermatozoa motility within the minimum normal range of 32%, following 60 minutes of exposure. The silicone-based vaginal lubricant produced similar results to the oil-based vaginal lubricant, however the progressive spermatozoa motility dropped below the minimum normal range within 60 minutes of exposure. The fertility lubricant did not produce mean progressive motilities that were within the normal minimum range at any of the three time intervals, producing poor results overall. The vaginal lubricant which produced the poorest results was the water-based, which immobilized all of the spermatozoa within 5 minutes of exposure and killed on average 95.23% within 60 minutes. Although further assessment is required, these results highlight potential fertility issues related to the formulation of commercially available vaginal lubricants.

A comparison of ABAcard(®) p30 and RSID™-Semen test kits for forensic semen identification.

The screening and confirmatory tests available to a forensic laboratory allow evidence to be examined for the presence of bodily fluids. With the majority of evidence being submitted involving sexual assaults, it is important to have confirmatory tests for the identification of semen that are straightforward, quick, and reliable. The purpose of this study was to compare two commonly used semen identification kits utilized by forensic laboratories: ABAcard(®) p30 and Rapid Stain Identification of Human Semen (RSID™-Semen). These kits were assessed with aged semen stains, fresh and frozen post-vasectomy semen, post-coital samples collected on different substrates, post-vasectomy semen mixed with blood, saliva, and urine, a series of swabs collected at increasing time intervals after sexual intercourse, and multiple non-semen samples. The test kits were compared on the basis of sensitivity, specificity, and the cost and time effectiveness of each protocol. Overall, both semen identification tests performed well in the studies. Both kits proved specificity for identifying semen, however the ABAcard(®) p30 test surpassed the RSID™-Semen test in sensitivity, cost per test, and simplified test protocol.